<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="style.css">
    <style></style>
</head>
<body>
    <div></div>
    <!-- css引用方式：行内样式、内联样式、外联样式 -->
    <!-- 下面这些都是块级元素，宽度都是100% -->
    <header>
        <h1>
            <img src="images/logo.png" alt="飞书官网">
        </h1>
        <nav>
            <a href="">首页</a>
            <a href="">个人中心</a>
            <a href="">首页</a>
            <a href="">个人中心</a>
            <a href="">首页</a>
            <a href="">个人中心</a>
        </nav>
        <div>
            <button>飞书网页版</button>
            <button>下载飞书</button>
            <button>飞书网页版</button>
            <button>下载飞书</button>
        </div>
    </header>
    <main>
        <div class="main-container">
            <aside>
                <ul>
                    <li>消息</li>
                    <li>日历</li>
                </ul>
            </aside>
            <section style="width: 80%">
                <section>111</section>
                <section>222</section>
                <section>333</section>
                <section>444</section>
                <section>555</section>
            </section>
        </div>
        <form action="">
            <input type="email" required/>
            <button type="submit">提交</button>
        </form>
    </main>
    <!-- <footer>3</footer> -->
</body>
</html>